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J.Lance · 09-05-2004, 02:33 PM

It is somewhat emissions related. It is a vacuum advance cutoff. It basically allows no timing advance until the motor has warmed up to operating temperature. The wiring would connect to one or two relays attached to the firewall either next to the fuse block or near the heater box. A 2nd temp. sending unit located on the passenger side of the block would trip the solenoid and open of vacuum to the distributor when it warmed up. If you look on the passenger side of teh block between the 6th and 8th cylinders, you should be able to see the sending unit or at least a plug where it once was.

Unless you're going back to stock, feel free to remove it along with the associated wiring. Your vacuum advance for the dist. should be hooked up to the carb where the vacuum solenoid is currently hooked to (ported vacuum). The wiring harness going up to the relays on the firewall and down to the sending unit is self contained and can be removed without cutting into any of the engine harness.

Hope this helps you out.

09-05-2004, 02:33 PM	#2
J.Lance Too many is never enough! Join Date: May 2003 Location: Idaho Falls, ID Posts: 455	advance cut off It is somewhat emissions related. It is a vacuum advance cutoff. It basically allows no timing advance until the motor has warmed up to operating temperature. The wiring would connect to one or two relays attached to the firewall either next to the fuse block or near the heater box. A 2nd temp. sending unit located on the passenger side of the block would trip the solenoid and open of vacuum to the distributor when it warmed up. If you look on the passenger side of teh block between the 6th and 8th cylinders, you should be able to see the sending unit or at least a plug where it once was. Unless you're going back to stock, feel free to remove it along with the associated wiring. Your vacuum advance for the dist. should be hooked up to the carb where the vacuum solenoid is currently hooked to (ported vacuum). The wiring harness going up to the relays on the firewall and down to the sending unit is self contained and can be removed without cutting into any of the engine harness. Hope this helps you out. __________________ Jason 1968 K10 SWB Fleetside 1971 K2500 GMC LWB 1968 K20 (later frame, donor body) 1972 C20 LWB parts truck 1993 K2500 Suburban, tow rig, 454, 4L80E NEW!! 18' Siem's car hauler 2004 Honda Odyssey (family man!)